Blank holder cushion



J 1952 R. c. meansou. 8 6

BLANK HOLDER CUSHION Filed Jan. 2, 1948 fnz /nz orr $9} C In 713011 IPatented Jan. 8, 1952 BLANK HOLDER GUSHIGN sl e A 0, 111;, a corpora amtajpes zidgmn eak re ult,

in phe euspion is malm Additional objects, features and advantages ofthe invention disclosed herein will be apparent to persons skilled inthe art after the construction and operation are understood from thewithembodying the features of the present invention;

Fig. 2 is a perspective view of an accumulator which may beadvantageously adjunctively employed with the blank holder cushiondepicted in Fig. 1; and

Fig. 3 is a fragmentary sectionalview of a blank holder cushion meansemployed as a modification of the blank holder cushion means depicted inFig. l. e

The drawing is to be understood as being'more or less of a schematiccharacter for the purpose ofillustrating and disclosin a typical orpreferred form of the improvements'contemplated herein, and in thedrawing like reference characters identify the same parts in the severalviews.

Referring to the drawing, particularly Fig. 1, wherein the blank holdercushion means with which the invention is particularly concerned anddesignated in its entirety by the numeral 20, is illustrated as beingadjunctively employed, for example, to a conventional double actionpress designated in its entirety by the letter A and comprising, ingeneral, a punch 21 of any particular shape, adraw'ring 22 complementaryL to the punch and adaptable to cooperate with said punch to form, forexample, the metal blank B which is advantageously held in position by ahold-down ring 23.

According to the construction of the invention, the metal blank B may beplaced between the draw rin 22 and the hold down ring 23, and suitablyclamped in this position by an outer ram 24 of the pressA which isadjustable to exert the necessary predetermined pressure to permit thepunch 2| to draw the metal blank B without either breaking the bottom orwrinkling the sides thereof. It is notable that too great a pressurewill prohibit the proper, fiow of metal and cause breakage or tearingduring drawing operations, whereas too little pressure will permit tooeasy flow of the metal, thereby permitting objectionable wrinkles toform;

"Since the invention is not particularly concerned with the preciseconstruction of theillustrated double action press or its associatedparts, they will not be further described in detail, and it is deemedsuflicient for all intents and purposes herein contained to show only.portions thereof adjacent to and cooperating with the possibleadaptation of the blank holder cushion means as contemplated herein andhaving described the general environment surrounding said adaptation,the specific construction and cooperating functions of the parts of saidblank holder cushion means with which the present invention isparticularly concerned, will now be described in detail.

In the exemplary embodiment of the invention depicted in Fig. 1, theblank holder cushion means is shown as being adjunctively employed, forexample, to the double action press A, said blank holder cushion meanscomprising, in general, a blank holder bottom member of any particularshape and being removably secured to the hold-down ring 23 as shown, a

blank holder top member 3| operatively associated with said blank holderbottom member 30 to define a suitable chamber 32 defined by surfaces ofthe blank holder top member 3| and the blank holder bottom member 30 andadaptable to receive and retain a suitable hydraulic fluid to provide ahydraulic cushion between 7 said blank holder top member and said holderblank holder cushion means contemplated herein.

bottom member, thereby to maintain a constant predetermined equalizingpressure on the blank A which is being held between the hold down ring23 and the draw ring 22 as shown, whereby equal pressure upon the blankB will be maintained regardless of gauge variations and variations inthe thickness and characteristics of the metal stock. An accumulatormeans designated in its entirety by the numeral (Fig. 2) is operativelyconnected to said chamber 32, said accumulator means comprising acylinder and piston arrangement adaptable to maintain a constanthydraulic pressure within the chamber 32. Although I have illustratedone form of accumulator means, it is readily apparent that other formshaving the same characteristics may be employed, such as, for example, aconstant pressure pump with arelief valve (not shown),

such pumps being sometimes termed as a pressure unloading pump, or anyother means may be employed which will allow the selection of a variableconstant predetermined pressure.

In accordance with the construction of the present invention the blankholder bottom member 30 is fixedly secured to the hold down ring 23 bymeans of securing means such as, for example, the bolts having threadedends adaptable to be received into suitably threaded apertures 46 in thehold down ring 23. Preferably, the blank holder bottom member 30 is acasting having a suitable surface 41 complementary to a related surface48 of the hold down ring 23. It is notable that suitable recesses havebeen em- 'ployed between the complementary surfaces 4'! and 48 so thatproper alignment between the blank holder bottom member 30 and the holddown ring 23 may be maintained.

Suitable pipe connections as at 50 are employed to operatively connectthe chamber 32 with the accumulator means 40 or the pressure unloadingpump hereinbefore mentioned, depending on which is employed. These pipeconnections may be of any suitable construction pref erably of aflexible type. r f

In orderto prevent'the hydraulic fluid from leaking from the chamber 32,there is provided a suitable packing ring 39 operatively disposedbetween complementary surfaces of the blank holder top member and theblank holder bottom member and adapted to retain the hydraulic fluid inthe chamber 32. ,It can be seen that the seer-see ceive threaded sad 130pe connecapnea which is *co I M a ted as theaccumulator means; 7 I

draulic systeinherein efere'd provided a passageway -tt in .top member3| i an in cpeaeemm an I the chamber =32; A suitable valve' means ispre- -titled as at "31- to provide a means-for permitting airin'thesystem to be bledtheretromfi 1 blank holder-top hieinber al maybe'made of -la casting rcr edreneahesecretes csmpiame "tai y to top-surraces crane bl'a to! membei flfl. -saom"-F v that the blanklioldezpImlnbel Gt disposed "its operelti-velpositior n a manner sothatit maybe moved upward oi'. .downwardly due to the tunctionalreaction oflthehydraulic flu-id in the chamber 32 It is notable: that the movementor'the blank holder member -3iin-the upward direction 'is restricted asto amount by means of the bolts fit ivhich 'a're providedwi-tha suitablecap =56 adaptable to engage a seat 53, which engagement is adaptabletof-restrict any further upward movement i espect "to the blank holderbottom member 31). Moreovehthe degree or upward movement may be adtustedby reguiation bf the distance the' bol-ts 55 am re ceived. into thesuitably threaded apertures- 58 in the blankholde'rbottm member suchadjustmnt' be-ing maintained in locked position by means of auitableiamhnutifl,

In accordance with the construction of the present invention, downward.pressure upon. the blank holder top member 3! isexe'rted by an out.-Side ram .m mbst- 2. in the-deadbea the arrow 60 in Fig. 1.""Since thepssure exerted by the ac sm-bet- T11 may be seen d posedin the chamber aA iorinly distributedpressure "upon thef'bl [B regardless ofgaugevariations variations 'in the thicknessjangla ..haragt,e ristigs ofthe metal stock. It can be seen th 1; the pressure uponthe blank B'wouldvary fror' Q ith'e "diiferences' in g g si'iccessive'blanksof metal ck."It is of paramount importance in drawing operations of the typecontemplated herein that the pressure be equal with respect to eachpiece of metal stock employed. Too great a pressure will prohibit theproper flow of metal and cause breakage, whereas too little a pressurewill permit too easy a flow of the material and permit wrinkles to formduring the drawing operation. Without equalized pressure, excessivescrap and waste in drawing operations would occur because of thenonadjustability of present day double action presses to compensate forsuch hereinbe'fore described variations in metal stock thicknesses.

Adverting to Fig. 3 wherein a modified structure of the presentinvention is illustrated, it can be seen that a tube-like member El isoperatively disposed in the chamber 32 of the embodiment shown inFig. 1. In accordance with the construction of the embodimentillustrated in Fig. 3 the blank holder cushion comprises, in general, ablank holder bottom member 62, a blank holder top member 63, a tube-likemember 6| made of a flexible material such as, for example, rubber 5 andbeing adaptable to receive and retain a suit able hydraulic fltiid,"saidtu-b'e like member being operatively is osed-teamed s'a-id' blankholder bottom member 3:! and racing adaptable to maintain a constantpressure the blank B which is'be-ingheld between the hold down ringtit-and the draw-ring 22 as shown in Fig. '1, whereby equafpressure uponthe blank B will be-maintained regardless of gauge variations inthethiokness and characteristics of the metal stock, and a means, suchas a pipe 59 operatively connected to said tube-like member 6| andadaptable to maintain a constant variable hydraulic' pressure within thetube-like member 64.

Adverting to Fig. 2,'wherein there isil lustrated one form adaptableto-maintain a constant variable hydraulic pressure, the accumulatormeans all? comprises'i-n generala cylinder is having-operativelydisposed ther' a piston it operated by a suitable hydraulic time 13-,said piston havinga predetermined number of weights it related theretoby means of a lever-"arrangement it, said cylinder being operativelyconnectedte the chamber 32 of the tube-like members-i, depending uponwhich one of the two designs'is employed, by means of suitable flexibletubing as at 58-. Iscan be seen that the lever arrangement will .cause apredetermined-pressure upon the piston which will cause the compressionof the hy-- drau-lic flu-id 'il in thecylinder which pressure in turnwill be transmitted to the chamber 32 or to the tube-like member at, asthe case may-be, by means of the flexible hose 50:, whereby-an equalpressure will be maintained'upon the blank piece B regardless ofvariations thickness ofthe metal stock. The amount ofpressure desiredmaybe obtained by the removal or addition of weights 73. Moreover, thedevice contemplated herein will compensate for. such variations in thethicknessof-the metal stockbycausing variations in the. amount ofhydraulic fluid contained in the chamber 32 or the tube-like member M,as the-case may be. It isdmportantto understand that the differential inthe thickness of metal stock is transmitted through the chamber 32 orthe-tube-likemember 64 which causesjthevariations of the amountof-hydraulic fluid contained within such chamber 3-2 or such tube-likemem ber 61 and such excessive fluid will be caused to flow between saidchamber] or; said member and the cylinder 75- of the accumulator 4i].Equal pressure atall times is maintained by the, provision of theWeighted piston arrangement hereinbefore described and illustrated inthe drawing.

While the illustrated accumulator means All may be advantageouslyemployed in the construction of the present invention, it can be seenthat other forms may be readily substituted, such as,

,for example, a constant pressure pump with a relief valve, such pumpsometimes being termed a pressure unloading pump, or any other means maybe advantageously employed which will allow the selection of a constantvariable predetermined pressure. It is apparent that such devices, whenadjunctively employed to the blank holder cushion arrangementhereinbefore described and with which the present invention isparticularly concerned, each will accomplish the same results and arereplaceable one by the other.

It is notable that the mechanism disclosed herein may be advantageouslyemployed in mass production manufacturing methods where quick and easydrawing operations result in economies in manufacture which determinethe final cost of the units drawn.

From the foregoing disclosure, it may be observed that I have provided ablank holder cushion which efiiciently fulfills the objects thereof ashereinbefore set forth and provides numerous advantages which may besummarized as follows:

1. structurally simple, efficient and durable; 2. Economical tomanufacture and readily adaptable to mass production manufacturingprinciples; and

3. The provision of a blank holder cushion readily adaptable forinporporation in double action presses and providing a constantequalizing predetermined'pressure on the blank positioned therein,regardless of gauge variation of the metal blank.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of myinvention and I do not wish to be limited to the precise details ofconstruction set forth but wish to avail myself of all changes withinthe scope of the appended claims.

I claim:

1. A blank drawing press comprising a drawing punch, a drawing diearranged to receive said punch, a hold-down member associated with saiddie for holding a blank in position, pressure means for urging saidhold-down member toward said die, pressure distributing means interposedbetween said hold-down member and said pressure means comprising a firstblock disposed about said punch and having a channel formed thereinsurrounding said punch, a second block disposed about said punch andassociated with said first block, a complementary protruding portion ofsaid second block extending into said channel to define therewith anenclosed pressure chamber, a surface of said second block bearingagainst an opposed surface of said holddown member, said opposed bearingsurfaces having complementary recessed and shouldered portions for thepurpose of aligning said holddown member and said pressure distributingmeans, means carried by one of said blocks and connected to the other ofsaid blocks for limiting the movement of said blocks in oppositedirections, sealing means interposed between saidprotruding portion andthe walls of said channel to prevent leakage from said chamber, ahydraulic fluid in said chamber, and accumulator means connected .tosaid chamber for supplying and maintaining a predetermined hydraulicpressure in said chamber.

2. A blank drawing press comprising a drawing punch, a drawing diearranged to receive said punch, a hold-down member associated with saiddie for holding a blank in position, pressure means for urging saidhold-down member toward said die, pressure distributing means interposedbetween said hold-down member and said pressure means comprising a firstblock disposed about said punch and having a channel formed thereinsurrounding said punch, a second block disposed about said punch andassociated with said first block, a complementary protruding portionofsaid second block extending into said channel to define therewith anenclosed pressure chamber, a surface of said second block bearingagainst an opposed surface of said holddown member, said opposed bearingsurfaces having complementary recessed and shouldered portions for thepurpose of aligning said holddown member and said pressure distributingmeans, means carried by one of said blocks and connected to the other ofsaid blocks for limiting the movement of said blocks in oppositedirections, sealing means interposed between said protruding portion andthe walls of said channel to prevent leakage from said chamber, ahydraulic fluid in said chamber, accumulator means connected to saidchamber for supplying and maintaining a predetermined hydraulic pressurein said chamber, and a vent passage defining means including a controlvalve for controlling venting of air trapped in said pressure chamberconnected to the side of said pressure chamber.

ROY C. INGERSOLL.

- REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number 7 Name Date 349,718 Hollerith Sept. 28,1886 1,503,131 Nelson July 29, 1924 1,562,953 Glasner Nov. 24, 19251,844,250 Hawkins Feb. 9, 1932 1,966,758 Haverbepk July 17, 19342,224,956 Ernst Dec, 1'7, 1940 FOREIGN PATENTS Number Country Date136,634 Germany 1902 652,601 Germany 1937

